The present invention relates, in general, to the field of AGC circuits and methods. More particularly, the present invention relates to an AGC circuit including a precision voltage clamp and method of especial usefulness in a fiber optic receiver for receipt of red, green and blue (RGB) data transmission.
It has long been known that fiber optic links can provide significant advantages in signal transmission over conventional techniques using coaxial cable, twin lead or twisted conductor pairs. Such wires are inherently susceptible to the pick up of external interference thereby distorting signal transmission. Further, these wiring techniques require significantly increased driving currents in signal transmission as the length of the interconnecting wire and signal bandwidth requirements increase due to their inherent capacitance as well as other attenuating factors. Importantly, these conventional techniques themselves can never be made completely free of the spurious RF signal transmission, particularly as their length is increased or as relatively high frequency signals are applied. This drawback is especially serious when variable frequency signals are to be transmitted such that the potential RF emission is likewise variable and cannot be specifically suppressed at a given frequency.
Heretofore, fiber optic signal transmission has been known to alleviate the above shortcomings of conventional wiring techniques. However, such systems have not supplied sufficient system bandwidth for many high frequency applications (120 mHz or greater) while being capable of operation over fiber optic lengths on the order of one kilometer or more. Moreover, those systems which have existed have been unreasonably complex and cumbersome and, by their very nature, prohibitively expensive for most applications.